The Portuguese Sundew (Drosophyllum lusitanicum Link.) 

in nature and cultivation

 Jan Flísek & Kamil Pásek

H. F. Link described the Portuguese Sundew (Drosophyllum lusitanicum Link.) in 1806, but the first references have been dated back to the 17th century. The genus name, Drosophyllum, is derived from the Greek DROSOS (meaning dew) and PHYLLON (meaning tribe or leaf). The species name is derived from Lusitania (from Latin), the ancient name for Portugal. In its native habitat, Drosophyllum is relatively rare, with plants growing in narrow coastal or maritime regions (maximum of a few tens of kilometers from the coast) with regular morning fogs during summer. Besides Portugal, Drosophyllum has been found in Andalusia (southwestern Spain) and in northern Morocco. Drosophyllum lusitanicum is the only extant species classed in the new monotypic genus of the family Drosophyllaceae Chrtek et al., 1989, 1996). The listed number of chromosomes is 2n = 12 (Heubl et al., 1997).

Drosophyllum lusitanicum is shrub-like carnivorous plant that can grow to be 1.5 m in height, but is usually shorter (about 40 cm). The stem is 5-15 mm thick and creeps along the ground when it becomes longer. The narrow, triangular leaves typically reach lengths of 10-25 cm with a width of 2.5 mm. The leaves can be longer in cultivation. Ten or more needle-like leaves are generally found per apical rosette. Older plants may develop side branches (or stems) during seed production, when suppressed buds in the leaf axils start to grow. These new side branches develop on both the long, ligneous and very sturdy stems of mature plants as well as on young plants. The rosette of leaves are typically 20 - 40 cm in diameter and consist of the apical “crest” of living leaves and dead leaves drooping down to the ground forming a dense tangle. With a little imagination, we see why the English common name “dewy pine” is used for this plant, as it looks very much like a small pine. The Portuguese call this plant “Pinheiro baboso”, which, translated means “slobbering” pine (Porto, personal communication). Native people of southern Spain in the Alcala de los Gazules region call it “La Gazul” (Schmidt, 1997). Drosophyllum is a perennial in nature and cultivation, but precise information about the maximum lifespan of this plant has not yet been published.

The Portuguese Sundew is a very interesting and curious plant for several reasons. Compared with other carnivorous plants, it is one of the most successful “hunters” in terms of quantity of captured prey, and all with absolutely passive primitive adhesive traps (stalked clammy glands) only. Also, there are certain morphological and anatomical curiosities particular to Drosophyllum. Some observations indicate that Drosophyllum is more archaic than previously assumed, an unusual fact considering its classification within advanced flowering plants (Magnoliophyta). Morphological features (missing specific dividing coir - cambium an endodermis in the stem, characteristic surface of stem, shape of leaves, spirally twisted ends of leaves, etc.) indicate that Drosophyllum may be closely related to ferns (Studnička, 1984b).

Drosophyllum is interesting in that it has two types of glands on the leaves; the huge stalked glands that attract and trap prey and the sessile, digestive glands (Juniper et al., 1989). Production of the mucilage for trapping prey is so intense that slime often drips from the leaves. Digestion of prey is very rapid, being complete within several days. Luring is accomplished by the sweet, honey-like odor of the mucilage, detectable even by the human nose.

In its native habitat, flowering occurs between February and May, sometimes later. The bright yellow, regular, quinate flowers can be up to 4 cm in diameter and are borne in groups of 3 - 15.  Rarely do the flowers grow separately. The self-fertile flowers open gradually for several hours during the day. Seed matures in approximately one month in the cone-shaped translucent seedpod. This splits open at the top, revealing opaque black, grooved pear-shaped seeds, about 2.5 mm in diameter. One seedpod contains about 3-10 seeds. Wind slowly shakes out seed for many months. Seed germinates during the first autumn rains. Seedlings grow quickly, and, in their native habitat, flower in the second year. A high germination rate is observed for seed that has been stored for several years.

Drosophyllum lusitanicum grows in the sun under  loose overgrowth. The underbrush consists of dry shrubs of various sizes, e.g. Cistus, Cytisus, Lavandula, Sarothamnus and Ulex (Studnička, 1984). Drosophyllum is also found growing alongside plants from the following genera; Bellis, Calluna, Carex, Festuca, Halimium, Chamaespartium, Polygala, Quercus, Tuberaria etc. (Schmidt, 1997). Soil on the south coast of Spain is sandy or loamy, slightly acid to neutral, lime-less and poor in nutrients. The geologic underlay consists of sandstone. Drosophyllum also grows directly in sandstone crevices. The natural lack of nutrients in the soil is overcome in Drosophyllum by the digestion of a prey trapped by the leaves and active secretion of digestive mucilage.

We acquired information on two Portuguese localities nearby Lisbon from Miguel Porto (personal communication, 2000) who was able to observe Drosophyllum in its native habitat. The plants grew in mixture of red sandstone and loam. Soil tended to be loamier than sandy and was mixed with organic material (pine needles). The second population grew in pure solid loam with no organic ingredients. Plants grew amongst cork oak (Quercus suber) scrub.  Surprisingly, plants at the second location were growing about 200 km inland near Portalegre. The reason for the colonization of Drosophyllum here appears to be human intervention.  People regularly harvest the cork oak and, in the process, clear the soil of vegetation. This removal appears to have allowed Drosophyllum to successfully establish itself there (Miguel Porto, personal communication). Further, regular cleaning of the soil has led to this area being dominated by young plants, as opposed to the first location which contained many older plants (Miguel Porto, personal communication).

The literature often indicates that Drosophyllum prefers to grow in alkaline substrates (Slack, 1988; Lecoufle, 1990; D’Amato, 1998). We are not sure whether this data is based on observations in nature or logical deductions and speculations only. More field research is needed to support or discredit this data. During our observations in its native habitat, we have never seen Drosophyllum growing in alkaline soils, despite several intensive searches at suitable places. Juniper et al. (1989) also cites that Drosophyllum keeps away from limestone areas. Miguel Porto (personal communication, 2000) in Portugal reaffirmed this in a subsequent survey. Another widely perpetuated myth is that Drosophyllum plants do not grow close to each other in its native habitat due to the production of inhibitors which suppress the growth of surrounding plants (Pietropaolo et al., 1986; D’Amato, 1998). According to our observations in nature and cultivation and also investigations by Miguel Porto (personal communication, 2000), the plants can grow side by side (several centimeters distance) without any negative influence on their growth. The fact that at some localities Drosophyllum is dispersed over large distances is likely the result of very harsh conditions and high mortality of the small seedlings rather than inhibitor production.

Summer climate at locations where Drosophyllum grows is characterized by a lack of rainfall. The proximity to the sea becomes very advantageous as the ocean provides a source of sufficient air humidity during rainless periods. Drosophyllum has an interesting life strategy developed to catch condensed moisture from air humidity. The stem, which consists of a rosette of long thin leaves, keeps close to the ground where there is always greater quanitites of morning dew for a longer period of time as compared to areas further above the soil level. Undeveloped leaves can absorb water too. Thus, Drosophyllum acquires necessary moisture even during the summer period, when there is no rainfall.

We had the fortune of observing Drosophyllum in its native habitat at three localities during our August 1999 visit to Andalusia, Cádiz in southern Spain. Our friends Christian Breckpot (Belgium), Alexander Schmidt and Jan Schlauer (Germany) made looking for these plants easier by providing precise range maps of the plants. They have our thanks, as the maps saved a lot of time! A visit of the Drosophyllum localities was one part of our great expedition of looking for European carnivorous plants, especially Pinguicula. We had driven 10,500 km in 21 days, saw 41 localities and discovered 33 species, subspecies and hybrids of carnivorous plants. However, to stick with the theme of this article, we will write about our observations on the other carnivorous plants and on the preparations made for this expedition another time. A surprise for the future!

Some notes about the Drosophyllum localities from our itinerary are provided below, including our field observations of the plants. 

August 4, 1999 Wednesday

…Under the cover of dusk, we were looking for car parking at 3100m a.s.l. (above sea level) on the way to the top of Pico de Veleta (3392 m.n.m) in the Sierra Nevada mountains of southern Spain.  The nearby Mulhacen (3481 m.n.m.), the highest mountain of the Pyrenean peninsula, was bathed in the setting sun. We had gone through a long tiresome march and successfully found the alpine butterwort Pinguicula nevadensis. During our return trip we passed within twenty metres of an ibex (mountain goat)! We found our car with great difficulties, given the relative darkness. At half past eleven, travelling down a zigzagging road from the mountain Pico de Veleta, we said good bye to the luminous town of Granada, beautifully spread out in the valley deep below the road. The weather was cold, about 5°C. While we were weary with our days visit of the Pinguicula vallisneriifolia locality in the Sierra de Segura mountains and the two highland localities of P. nevadensis, we were still looking forward to observing our first Drosophyllum. We decided to overnight about 300 km along the southwestern road leading to Malaga and Gibraltar.

 August 5,1999 Thursday

About one thirty in the morning we made a pit stop in front of the illuminated theatre in Malaga to brew the necessary coffee. There was a nighttime hustle and bustle in this place and the temperature was warm at around thirty degrees. Within two hours we had descended from 3100 m a.s.l. to 0 m a.s.l.. The change of 25°C between elevations in so short a time was really felt by us.

At four in the morning we finally found a suitable campsite near an abandoned dusty road winding its way to the low coastal hills between the cities of San Roque and Estepona. These hills are covered by dozens of wind power stations, which use the energy of all available wind from the sea to the land. At 4:30 we lay down in our tents near one of the wind power stations and fell asleep listening to the never-ending and not so silent sound made by the rotating vanes. At 8:30 we awoke and admired our beautiful view of the sea! During the 4 hours we spent camping, about 20 cars had come along for the nice view. Overall, our sleep was not a quiet one!  We woke up to find we had camped along newly burnt cork woods, something we missed at four thirty in the morning.  A decision was made to visit the most southern point of the European continent - the town of Tarifa - and then bathe along the border between the Mediterranean Sea and Atlantic Ocean.

At 9:30 we were on a beach representing the most southern point of our expedition. A sprinkling of drunk Austrians and Frenchmen sleeping away their late night binges was all that existed for human life. Otherwise, there was no one anywhere. The bath in the sea was refreshing but cold (12°C). Early-morning clouds hid the sky covering nearby Africa. The ocean was turbulent and dark. We refuelled energy really needed for the upcoming day. We didn’t know it then, but we would fondly remember the cool maritime morning and cold refreshing bath over the next few days!

A photo of our “group of four” was taken and, with a last glance towards Africa, said good bye to this beautiful place. Following the rocky Gibraltar shore, we turn off on to a road leading inland towards a Drosophyllum locality near the town of Algeciras. Shortly before lunch, the clouds disappeared and the sun began to beat down. People who love the sun and heat would really enjoy it here in the south. We decided to have lunch under the shadow of domesticated blue gums. A Drosophyllum locality was subsequently found without any problems.

 The site consisted primarily of a sharp, uncovered, eroded slope arising from a landslide or mining. We had already seen the magnificent tall Drosophyllum plants from a distance, but up close found that the slope was covered with plants. The plants were generally widely dispersed but were also found growing nearby in clumps. We also found a few young plants, this year’s seedlings. We were in rapture and started to fully exploring this locality.

There were several hundreds of plants of various ages in an area approximately 30 m long by 15 m wide. The plants grew in an absolutely dry area on a south slope at an altitude of 100 m.n.m about 20 km from seashore and were exposed to the sun all day. Nonetheless, drops of dew glittered brightly in the southerly sun. A deep root system likely provided a lot of the necessary water in this streamless landscape.

Uncovered slopes revealed the geologic profile at this location. The upper layer (about 1 m) consisted of yellow loam and conglomerate loamy soil, while the lower layer consisted of a sprinkling of sandstone rocks, stones and gravel mixed with sandy-loamy soils. The soil was dry, dusty and very cumbly. The light slope and plain beneath the landslide were overgrown with impenetrable small prickly shrubs and other vegetation. The recently disturbed slope had little vegetation, covered primarily by Drosophyllum. It is clear that Drosophyllum did so well here because the plants had minimal competition with other plants and had suitable conditions for germination and growth. It is possible that ongoing erosion and landslides limit the growth of the other plants. Some Drosophyllum grew in a short bushy zone of surrounding vegetation but were nowhere near as beautiful and robust as the ones on the slope. It is clear that intermittent fire would liekly help Drosophyllum seedlings by removing other competitive plants. Carnivorous plants benefitting from fire is not unusual and has been described before. For example, North American Pitcher Plants (Sarracenia) and the Venus Fly Trap (Dionaea muscipula) or Australian sundews (Drosera), Rainbow Plants (Byblis) and Australian Pitcher Plant (Cephalotus follicularis), all benefit from regular fires which ensure plenty of suitable biotopes, where the plants do not have to compete with other species. The question remains as to how much fire the single mature plants are able to withstand. It is clear that the plants and seed can survive short-term, high temperature fires as indicated by their large numbers and the age of some specimens at this site. Nearby burnt trunks indicated recent passage of fire.

There were old plants on the slope, whose age we were unable to estimate, and small seedlings from the past season’s seed. These plants are the most beautiful looking in their native habitat. They were huge and well branched with stems up 10-20 cm, and rosettes of leaves up to 15-30 cm in diameter. We even found two plants with 50 cm diameter rosettes!!! Every plant had several leaves. Seed had matured long ago, leaving only empty seedpods. Nonetheless, we did find one late flowering plant. A midday temperature measured near the stem of one plant (1 cm under the surface of soil) was 42°C!!!

After an hour and a half in full noon-hour sunshine, we left this beautiful place and headed towards the multiple larger localities on a part of a slope near Alcalá de Los Gazules. We were dying to see them!!! 

After about 40 km of driving, we parked our car along the dusty road and started to explore. The area appeared identical to the information provided to us on the maps, and all was going according to plan. However, after 5 hours of walking through underbrush (akin to walking through barbed wire) over shaggy hills and affirmations of highland goat shepherds that we are on the right route, we gave up. Fifteen kilometers on foot and scorching sun in excess of 45°C had made ruins of us. Torn trousers, legs and arms beaten-up, burnt and bloody, and nipping sweat in fresh wounds reflected our tortured travels on this terrain. We got in our steaming car. The coolest water to drink was about 60°C! After driving 7 km, we stumbled across an area that seemed suitable for exploration. We parked our car again and, although we were sick and tired of it, we decided to climb a mountain.  The first problem lay in the rapidly approaching nighttime, so we had to hurry up to allow us to return before dusk. The second problem was with incorrect Spanish tourist markers. Tens of unmarked and peculiarly marked pathways made it difficult to discern the correct course to the top. But in the end, it turned out that all the ways led to the top! We came to understand the Spanish markings during our return trip. Most of the tourist markers were chalked in a crossform and placed at the backside of stones and so were seen during the trip down! This marking is probably updated yearly, quite likely in spring, when rains wash out the old markers. Gold Czech marking!!!

We tried to quickly climb to the top, but found it rather difficult. Despite the advancing dusk, our exhaustion after the afternoon adventure and the never-ending climbing on the mountain, we found the first Drosophyllum.  Unfortunately, we did not have enough time to fully explore this locality, only a few minutes. The plants were at 750 to 800m a.s.l., in a zone some several hundreds meters above the zone containing cork oak (Quercus suber). And so, we only saw a tiny proportion of this interesting locality divided into specific vegetation zones like something from a textbook.

The plants were brown without any glittering drops of mucilage. They looked very miserable, most being dead. Although the plants grew approximately 650-700 m a. s. l.. higher than those at the first location, most of their seedpods were empty.  Surrounding, almost unpenetrable vegetation, was composed of junipers, prickly ilex oaks, small grasses and bushy shrubs. Drosophyllum fought for every free place. The soil consisted of sandstone, exposed in many areas. There were frequent fires at this location, however surrounding vegetation indicated that the last fire was some time ago. Photographs of this place from 1996 showed quite a different scene than what we had seen three years later. In these photos, sporadic underbrush and burnt shrub made-up the surrounding vegetation. There were magnificent unhindered Drosophyllum growing among these.

Our view of the plants was during the hot, dry season only. Drosophyllum is at its prime from autumn to spring, generally around May (Miguel Porto, personal communication). The plants can restrict their growth under poor conditions during the summer, with some appearing to die off. But, it is very likely that the plants will restore their growth with the first autumn rains. When we saw the withering and drying plants in summer, it did not mean that they would not rise once again with coming rainfalls!

We had to run back downhill, as dusk was upon us. After a few kilometers of driving, we found a beautiful campsite at the pastures near the town of Ubrique. Despite the persistent pain and blisters we fell asleep immediately.

August 6, 1999 Friday

We woke up at 8:00 in the morning.  The grey-white clouds gathered along the nearby hills. The clouds covered the tops of hills, gently sliding and falling along the slopes. An interesting view to wake up to. It looked as if it would begin to rain at any time. We packed our tents and sleeping bags and moved to the locality between the towns of Ubrique and Alcalá de los Gazules.  We had received a tip about a zone a few kilometers long where Drosophyllum grew directly alongside the road. At 9:30 our car climbed the adjoining hills and was encompassed in a dense white-grey fog. We could barely see ten meters ahead! A light drizzle fell on the slopes of the hills, covering everything in a thin film of water. Gentle breezes shifted the drizzle around the hillside. It was cold, about 12-15°C. There were condensed drops of dew on the soil and surrounding vegetation. Everything was completely wet!!! Now we could see how Drosophyllum acquires the necessary moisture in the dry summer season, especially when this event is a regular occurrence. We believe that this climate is very similar to the climate at other Drosophyllum localities. The previous day we had seen the same early-morning clouds over the tops of the Moroccan part of the Atlas Mountains, where Drosophyllum grows. The close vicinity of the Atlantic Ocean plays a very important role in such a dry period and may be a reason why the plants do not grow farther inland. At 10:30-11:00 the fog and clouds disappeared allowing the sun to begin to beat down again. Vegetation dried quickly and the temperature increased briskly. It would be another hot day.

The location we were looking for was found at about 700 a.s.l., a few kilometers from Ubrique. There was a marked road, about 20 km long, on the map without any further details. We very slowly drove this road in its entirety, watching the surrounding slopes carefully. Tired from the previous days adventures, we relied solely on finding plants from the car.  We called this method “car herbarizing”, useful for searching for populations of pitcher plants in the U.S.  or butterworts in Pyrenean. Unfortunately, it turned out that this method was not useful in searching for Drosophyllum which proved to be quite “invisible”. After 15 km we turned around and drove back along the way we came. This time, we applied a new strategy. We stopped at suitable places and got out to explore. By the sixth attempt, we were successful! It was shocking to find several plants growing on an eroded slope only a few centimeters away from the asphalt road. It meant that we had already driven by them once before!!! Interestingly, the plants were among the most beautiful Drosophyllum plants we had seen. The soil consisted of pulped sandstone and loam. The plants had almost empty seedpods. 

A few hundreds meters further along the road, we found more plants, heavily covered in dew, on a very mild sandstone rocky slope. There were only a few dozen of the mature plants and seedlings at this locality and they were not as beautiful and old as compared to the ones near Algeciras.  These plants were approximately one year old and had not reached flowering size. The rosette of leaves averaged about 20-25 cm in diameter. The plants had almost no stem, looking as though they had grown directly from the soil surface. It appeared that the plants grew directly in the rocky clefts and rifts in the horizontal sandstone rock. Dry soil was very sandy, consisting of pulped sandstone and sandstone gravel without loam. It was very similar to the mild pure white sand arising from the erosion of sandstone. There was not much other vegetation at this place. Needless to say, this location was exposed to full sun. It appeared as though this may have previously been a sandstone pit, now colonized by the classical Mediterranean vegetation. Drosophyllum were the first colonizers at this site. Surrounding slopes were overgrown with bushy vegetation and did not contain any Drosophyllum plants. One interesting observation was that of several pasturing cows nearby, which trampled and ate not only the surrounding vegetation, but most of the Drosophyllum!!! We found many broken stems of these rare plants with several of the plants resprouting again!

At 13:10 we said goodbye to this location and to the Drosophyllum. We started the almost 700-km long journey through streamless, but magnificent Spanish lands from the town of Cordoba to Madrid, and eventually to the locality of Pinguicula dertosensis. The sight of Drosophyllum lusitanicum in its native habitat was imprinted so firmly in our minds, that we would certainly have to return here again…

Common comments from our observations at Drosophyllum localities

Previously described localities are likely the most eastern ones in regions where Drosophyllum occurs. Drosophyllum grows in acid sand-loamy soil, in the sandstone clefts and cracks, in sandstone-loamy gravel and in pure sand. A sample of the more loamy than sandy soil from the superficial layer at the locality near Ubrique had a pH of 5.3. The plants prefer full sunlight and eroded places without any cover. Growth of the plants in the underbrush of shrubs and grasses is poor. Plants never grow in the shade of the oak woods. The plants can survive high temperatures for a long time (even 45°C) or light frosts (down to –7°C in cultivation) without any damage. Literature differs in what are the typical altitudes of incidence for Drosophyllum. Although some authors cites that the plants grow from sea level to 400m a.s.l. or lower, we observed Drosophyllum growing at altitudes up to 750-800m a.s.l..

Dewy plants always had a lot of prey. The rosette of leaves reached 15-25 cm in diameter. One rosette typically had 1-5 flower stems and 5-7 flowers per stem. One follicle contains 7 – 10 seeds. There were many young seedlings and old plants at the localities. The older plants branched approximately 4-5 times.

The growing range of Drosophyllum is limited to maritime regions with characteristic regular morning fogs bringing essential moisture in the summer periods, when no rain falls for several weeks. The surface of the soil was absolutely dry during our visit. When we had returned back via the inland region of Spain, we drove through the nearest adjoining mountains, Sierra de Grazalema, comprised primarily of limestone. There were no Drosophyllum there at all, although clouds from the Mediterranean Sea and Atlantic Ocean gathered in this area- in a few ridges high above 1000 a.s.l. of the mountains Sierra de Grazalema with the highest top Torreone (1654 m a.s.l.). Despite a lot of rain falls in these limestone mountains, the incidence of Drosophyllum has not been recorded there. May be the reason is that the plants do not grow in alkaline soils.

And why does Drosophyllum not grow further inland? As discussed above, Drosophyllum gathers moisture from regular morning fogs typical for the maritime regions. These morning fogs usually dissipate near the coast, generally between the first mountain ridges (as in the case of Sierra de Grazalema) and the coast. Hence, areas further inland from these mountain ranges are essentially fog-less. This lack of a regular source of water in summer is the reason why Drosophyllum does not grow in the dry central regions of Spain.

And one last interesting observation of Drosophyllum in its natural habitat. Our plants are grown in open outdoors-garden cultivation from spring to autumn. It is interesting to note that plants in the garden capture more insects than do the ones in nature. It was estimated that there was only 20-50% of the quantity of prey caught by plants in their natural habitat as compared to cultivated plants. All the plants were comparable in their size. How can this be explained? Could the lower quantity of insects at sunburned localities or a different generic composition of prey be the cause? Or is there an animal- "thief" at the localities which steals captured prey?

Cultivation

If you dip into current or even previous literature and articles about Drosophyllum cultivation, you will probably find information stating how artificial cultivation is difficult and almost impossible (Lecoufle, 1990). But some authors cite the opposite (Slack, 1988; Cheers, 1992). Over several years of cultivating these plants, we found that growing Drosophyllum is really very easy if you follow several basic principles of cultivation.

Despite some unaccounted-for data about asexual propagation in the literature (Lecoufle, 1990), Drosophyllum can be propagated by sowing seed only. One of the morpholgic peculiarties of Drosophyllum is that it does not produce adventitious roots and so stem cuttings cannot root (Studnička, 1984b; D’Amato, 1998). The fibrous root system is very susceptible to any damage and that is why the plant can not be repotted. The best time to sow the seed is in early spring.

We sow seed and subsequently grow plants on a medium consisting of acidic, fibrous peat moss and mild, nonalkaline sand (1:3). We sometimes add cut dry Sphagnum, perlite, vermiculite or milled charcoal, but this is not necessary. The plants tolerate loamy-sandy planting medium too. Plants grew very well in a sample of this soil we imported from the locality near Ubrique. We always use unglazed ceramic pots 12 cm or more in diameter. Some stems of sphagnum are put through the drainage hole to act as a wick. We fill a pot with the planting medium to 2 cm below the edge and press the substrate down. The filled pot is placed in a tray of water to moisten the substrate. Now we are ready to sow the seed.

The minute black seeds have a hard seed coat. For successful and quick germination, scarification is necessary – you must scratch the seed coat. We recommend the following methods: 

A) Before sowing you can soak the seed in water or 0.1% solution of giberellic acid (GA₃, stimulator of germination) for 24 hours. Then you carefully cut very thin slices of the soft seed coat using a knife blade. We cut at the peak of the seed, while other authors recommend cutting the side or a wider part of the seed. 

B) Dry seeds can be abraded using sandpaper or a rasp. This procedure crushes up the hard seed coat. It is better to use method A).

C) You can sow the seeds without scarification and place them in a heated greenhouse. Seed will naturally germinate in the spring. While method A) allows a more precise timing of germination, method C) unfortunately does not.

Prepared seeds are sown on the moist planting medium in 3 – 5 pits about 1 cm deep (dug by a finger). We put one seed into every pit. The previous recommendation of placing the pot in darkness (Studnička, 1984a) has been found to be unnecessary. In our experience the seeds germinate at the same rate when exposed to light. The statement that only one plant should be left in a pot after germination is also untrue. We always grow several plants (1 – 5) in a single pot without any problems. Their growth is comparable with the plants potted up individually.

Seeds germinate in ambient or slightly higher air humidity conditions within one or several weeks. Too high air humidity leads to death of the germinating seedlings. If seed is treated with giberellic acid (GA₃) they will start to germinate after one week. Otherwise, seed germinates within 2 – 3 weeks. As soon as the seed germinates you must decrease air humidity and increase air circulation. Also we add substrate to the germinating plants so that we cover the sowing pits with the substrate and replenish the surface of the pot. High air humidity will certainly kill all the young seedlings. Drosophyllum requires maximum light. About 40% of the germinated plants die during the first 2 – 3 months.

When the plants have grown a few centimeters, we have several possibilities on how to proceed. The first possibility is for growers who have the time to care for their plants. The pot is kept standing in a tray, adding water only when the plants require it.  The planting medium on the surface is kept dry or very slightly moist. Watering ensures a moist lower layer of the planting medium in a pot. You must closely watch for signs of wilting of the plant, especially on hot summer days. This is an indication to add water. Intermittent overwatering of the planting medium or temporarily reduced lighting is not a problem for mature plants. Drosophyllum can be grown very easily in trays on windowsills, where the plants are watered from below as needed. The planting medium must be kept moist not water-logged. The construction of so called “double pots” is not necessary. In comparison to the fragility of the young plants, mature ones tolerate waterlogging and dry spells better and seldomnly die from this.

If you have an outdoor peat bog, dig a spot into the substrate 5 – 10 cm deep for Drosophyllum. The lower part of the pot can be set into the holer, while the upper part of the pot will stick out of the surface. The upper layer of the substrate will dry up completely during hot summer days. The emergent part of the pot can be masked with some aerial or porous material such as large stones to give it a better look. Drosophyllum should be placed outdoors at the beginning of spring and brought indoors with the first frosts. The plants do not need protection against a few days worth of rain, as excess water flows through the substrate in the pot very quickly. 

The second possibile method for growing Drosophyllum requires the construction of a so-called “double pot”. This is suitable for growers who do not have the time to observe their plants every day and quickly respond to the need of water. This method is described well in Adrian Slack’s book (Slack, 1988).  The pot with germinated seedlings is placed on substrate or sphagnum which has been placed in a second ceramic or plastic pot with larger diameter filled so that two-thirds of the inner pot will be in the larger outer pot. A third of the pot with the plant juts above the edge of the first pot (vide picture). This “double pot” should be placed in a tray, always kept full of water. Watering should be higher in summer and lower in winter. The needed amount of water will penetrate through the bottom of the upper pot. The upper surface of the planting medium may dry up completely. It is necessary to keep the bottom of the inner pot rather high (vide picture) so that it does not sit in the water. If it is too low, the planting medium and roots would be waterlogged permanently.

Drosophyllum lusitanicum loves full sunlight all year round. The plants like high temperatures during the summer and fall and a range of 5-15°C in winter.  Permanent high air humidity is bad. This plant may be grown successfully in pots on the windowsill receiving full sunlight (south exposure is ideal). Of course, the greenhouse is an excellent location, especially in winter. We recommend outdoor cultivation of Drosophyllum during the summer, e.g. balconies, gardens or peat bogs. Using these methods, we have been able to grow the plants for several years without any problems or loss. Outdoor plants are brought inside with the first frosts, but will survive temperature falls to 0°C and even light frosts without damage (-7°C). The plants spend their dormant period in a cold and bright room. During the dormant period the planting medium must be drier. Before Drosophyllum are winterized, it beneficial to remove all old dry leaves, which could become a source of rot and rust infection. 

For the first time we tried burning the old leaves in December ’00 in place of laborious and long mechanical removal performed previously. Drosophyllum produces dozens of leaves during the growing season. When they die, they droop down to the ground forming a dense tangle of dead leaves that cover the plant stem. The combustion of the leaves was very quick and intensive, literally like a bolt of lightening. Several dozen of the old leaves incinerated in a few seconds. The flames were so intense that they burned the lower, living leaves, but left most other leaves, including the ones in the central rosette, undamaged. The old leaves were burnt away, leaving a charred stem. This experiment was performed on plants in two pots (I.: 7 plants / 7 tips / 2 young seedlings; II.: 3 older plants / 15 tips). After 14 days it was apparent that the fire did not damage the plants. All the plants survived including young seedlings! What do these results indicate? Fire that passes through the natural habitat of Drosophyllum where it grows sparsely with a few other shrubs and grasses, likely passes very quickly. It is clear the small amount of high heat (few seconds) does minimal damage to the plants and that they can survive fire without any problems.

In cultivation, Drosophyllum can flower all year round, mostly at the end of winter and during early spring. In exceptional cases, the plant starts to flower when it is only two months old. It is usually best to remove this flower in its early stage. The plants usually start to flower from 6 – 9 months when they are 40-55 cm in diameter. 

It is interesting to note that rain does not wash away freshly captured or partially digested prey, but light rain washes away completely digested insects. The plants remain "dewy" with clammy mucilage in the rain and water does not wash away the digestive secretions on the tentacles. Contrary to sundews (Drosera), these plants can capture large flies without any problems. In our experience the plants that capture plenty of prey grow more quickly than starving plants. 

What can be said at the conclusion of this article? We believe this article presented important information about this beautiful carnivorous plant. Perhaps we have instilled a yearning in you to cultivate this rarity! You can see for yourself that cultivation is not overly difficult. Good luck!!!

If somebody knows of another locality of this plant, please write us with more information about it. We are interested in your experiences with growing Drosophyllum, especially if using methods of cultivations different from the ones described above. Thank you.

We thank Christian Breckpot (Belgium) and Alexander Schmidt (Germany) for exact information about the incidence of the plants in nature. Lubomír Adamec (CZ), Jan Schlauer (Germany) and Miloslav Studnička (CZ) for scientific input. Our thanks belong to our travel-companions Martin Spousta (CZ) and Michal Parvanov (Slovakia) for precious commentaries on observations in native habitats and Miguel Porto (Portugal) for his findings from native localities in Portugal. We also thank Marek Svítek (CZ) for English translation and Chris Teichreb (Canada) and Phill Wilson (GB) for language corrections. Our thanks are also due to Vladimír Sedláček (CZ) for valuable financial support, without it, our journey would not have been realized. 

LITERATURE

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Poppinga S., 1997. Drosophyllum lusitanicum (L.) Link (1806) Portugiesisches Taublatt, Taublatt 30: 4-5.

Schmidt A., 1997. Drosophyllum lusitanicum an zwei Fundorten in der Provinz Cádiz, Südspanien, Taublatt 30: 5-14.

Slack A., 1988. Carnivorous Plants. Rev.ed. Alpha Books,  London.

Studnička M., 1984a. Masožravé rostliny. Academia, nakl. ČSAV, Praha.

Studnička M., 1984b. Masožravá rostlina rosnolist lusitánský. Živa 32 (5): 8-10.

Copyright (c) Kamil Pásek & Jan Flísek, 2001